Analog and electronic circuits
Learn the basics of analog circuits — op-amp properties, inverting amplifier gain and the cutoff frequency of RC filters — with multiple-choice questions.
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Analog and electronic circuits: key points
Analog circuits handle voltages and currents that change continuously. The operational amplifier, a typical component, is ideally treated as having infinite input impedance, zero output impedance and infinite gain.
The gain of inverting and non-inverting amplifiers with negative feedback, and the time constant and cutoff frequency of RC circuits, are common subjects for calculation questions.
All Analog and electronic circuits questions (50)
- Which combination correctly describes an ideal op-amp?
- In an inverting amplifier using an ideal op-amp, with input resistor Ri = 10 kΩ and feedback resistor Rf = 100 kΩ, what is the voltage gain?
- Which is closest to the cutoff frequency of an RC low-pass filter with R = 1 kΩ and C = 1 µF?
- In a non-inverting amplifier using an ideal op-amp, with input-side resistor R1 = 10 kΩ and feedback resistor R2 = 90 kΩ, what is the voltage gain?
- Which correctly describes a voltage follower using an op-amp?
- What is the effect of applying negative feedback to an amplifier?
- What does a large CMRR (common-mode rejection ratio) of a differential amplifier mean?
- What is a voltage gain of 100 expressed in decibels?
- What is the circuit called in which the feedback resistor of an op-amp inverting amplifier is replaced by a capacitor?
- Which expression gives the resonant frequency of a series LC circuit?
- What does a comparator do?
- An op-amp with a gain-bandwidth product (GBW) of 1 MHz is used to build a non-inverting amplifier with a gain of 10. What is the approximate bandwidth?
- What does the slew rate of an op-amp mean?
- What does an inverting amplifier do when several inputs are connected through resistors to its inverting input?
- What condition must a feedback oscillator satisfy to sustain oscillation?
- In an ideal op-amp circuit with negative feedback, what is the property called by which the two input terminals have almost the same voltage?
- Which correctly describes the input offset voltage of an op-amp?
- What is the characteristic of an RC circuit with a capacitor in series with the signal path and a resistor between the output and ground?
- Compared with a linear regulator (such as an LDO), which is a characteristic of a switching regulator?
- In the step response of an RC circuit, how long does it take for the capacitor voltage to reach about 63% of its final value?
- Which circuit converts a photodiode current into a voltage by feeding the current into the inverting input of an op-amp and converting it with a feedback resistor?
- Which amplifier, typically built from three op-amps, is used to amplify tiny differential signals from sensors with high precision?
- What increases the thermal noise (Johnson noise) voltage generated in a resistor?
- Which circuit adds two voltages with opposite temperature coefficients to create a reference voltage of about 1.2 V that hardly depends on temperature?
- Which circuit generates a clock at a frequency such as an integer multiple of a reference clock while locking its phase to the reference?
- What is the circuit called in which the input resistor of an op-amp inverting amplifier is replaced by a capacitor?
- Which circuit has different thresholds for rising and falling inputs and prevents the output from chattering due to noise?
- Which metric indicates how well a circuit keeps supply-voltage fluctuations from reaching its output?
- Which metric is used to judge whether a negative-feedback amplifier operates stably without oscillating?
- Compared with a class A amplifier, which is a characteristic of a class B push-pull amplifier?
- When a current of 1 mA flows through a 10 kΩ resistor, what is the voltage across it?
- What is the combined resistance of two 10 kΩ resistors connected in parallel?
- Two 10 kΩ resistors are connected in series across a 10 V supply. What is the voltage at the point between them (relative to ground)?
- How does the magnitude of a capacitor's impedance (capacitive reactance) change as frequency increases?
- How does the magnitude of an inductor's impedance change as frequency increases?
- Which correctly states Kirchhoff's current law (first law)?
- When a constant current keeps flowing into a capacitor, how does its voltage change?
- What does the "−3 dB" point in a filter's frequency response represent?
- In a Wheatstone bridge made of four resistors R1, R2, R3 and R4 (R1 and R2 in series, R3 and R4 in series, with the two pairs in parallel), what is the condition for no current to flow between the midpoints of the two pairs (balance)?
- Which correctly states Thevenin's theorem?
- What does a high Q (quality factor) of a resonant circuit mean?
- What is the output impedance of an ideal current source?
- Why are crystal oscillators widely used as clock sources for watches and microcontrollers?
- What does the dropout voltage of an LDO (low-dropout linear regulator) mean?
- For a circuit with first-order low-pass behavior, which approximately relates its bandwidth BW to its rise time tr for a step input? (10% to 90% rise time)
- Which correctly describes the idea of dominant-pole compensation used in op-amps?
- Which noise, particularly noticeable in MOSFETs, grows larger at lower frequencies?
- When a voltage is sampled onto a capacitor C through a switch, what is the RMS thermal noise voltage left on the capacitor? (k: Boltzmann constant, T: absolute temperature)
- Which correctly describes a Butterworth low-pass filter?
- In an inverting amplifier using a bipolar-input op-amp, why is a resistor equal to the parallel value of the input and feedback resistors placed between the non-inverting input and ground?